All of us know that fingerprints are used for personal identification for more than 100 years. It is the simplest and inexpensive method of identification. Fingerprints are the forensic scientist’s handiest tool to catch criminals, helped law agencies and produced as evidence in law of court.
What make Fingerprint science special?
Without the support and assistance of hand, no crime can be committed. The chances to find fingerprint marks are higher in any type of crime scene. It is now accepted throughout the world that the fingerprints science played a major role as evidence because of the following features –
The fingerprint patterns present on the first phalange of fingertips are varying from one person to another, they are different and unique. There duplication has not been observed. They remain unchanged and maintain the individuality of an individual throughout the life.
Throughout the life time of an individual fingerprint remain constant. Fingerprint ridges appear before birth i.e. during the third, fourth month of pregnancy and these are the last remaining feature after death of an individual. They are the natural identity card given to each individual.
All individuals on the earth carry this medium of identification, this makes them universal. A criminal always use his hands to commit any crime resulted in leaving fingermarks on the scene of crime or on any object, which come in contact with his fingers while committing the crime.
People have attempted several methods to imitate fingerprint but successful imitation of fingerprints is not reported so far. Any experienced expert can identify the forgery.
Fingerprints have different ridges characteristics and patterns which help the experts to systematically classify them.
Fingerprint Uniqueness in Twins
Twins are identical twins or fraternal twins, they share the same genetics but by taking their fingerprints you can distinguish between them.
When an expert says that two fingerprints are identical it means that both share the same pattern and similar ridges characteristics. These ridges characteristics are called minutiae. Latent fingerprints are also called hidden prints. These are the chance prints which leftover by the perpetrator by chance at the crime scene. Latent fingerprints are developed by experts at crime scene by powder method, chemical method or by using alternate light source.
The Myths of Fingerprints Science –
1) Fingerprints are forever
Fingerprints are forever but certain genetic conditions (Adermatoglyphia) and skin condition leads the loss or distortion of the fingerprints. Persons who are associated with tactile works, typist, clerks, individuals associated with message work, maids etc. also loss the fine ridges characteristics.
2) Humans are the only animals with fingerprints
Some animals like gorillas, chimpanzees and koalas have unique fingerprints. Koalas prints are looking similar to humans’ fingerprints.
3) DNA fingerprinting overshadow the fingerprint science
Most of the crime scenes don’t have blood and body fluids but chances of fingerprints are more as the objects/articles had been touched by criminals during the process of crime. So fingerprints are still the most commonly found evidence at the scene of crime.
4) System does all the work
A big misconception is that the computer system (AFIS-Automated Fingerprint Identification System) does all the work but the system is automated not automatic, it’s the expert who does the work. System or tools have been changed but analysis always requires an experienced expert.
5) Professional analysts are highly accurate, but not infallible
To understand this point first sees the difference between uniqueness of fingerprints and the exactness of fingerprint identification. Both these things are completely different. When a fingerprint lifted from a crime scene it is then searched in the database or with the suspect fingerprints. It is a process of observation, analysis and verification by the expert. Yes fingerprint are unique to every individual but to match the prints an experienced expert is needed, poorly trained analysts made damage to the fingerprint science.
In the year 2004, FBI arrested Oregon lawyer Brandon Mayfield for his involvement in Madrid train bombings. The basis of arrest was a partial fingerprint that matched with him. Later it was found that the experts were wrong in there analysis, actually the print was later matched with an Algerian man Daoud Ouhnane arrested by Spanish officials.
Fingerprint analysis is still an extremely effective tool because it’s done good work than harm. The errors occurred and brought to light- it was the science that conveyed them to light. If you make a mistake, you deserve to be analyzed. National Institute of Standards and Technology found in its study that the automated computerized systems match latent fingerprints are correct more than 99 percent of the time when matching fingerprints from two or more fingers.
6) Accuracy and consistency of forensic latent fingerprint decisions
Ten digit prints (for search purpose and matching) are of higher quality and collected under controlled conditions by ink method on prescribed form or digitally with the help of a live scanner system from a known subject.
Latent print examination is difficult because latent prints are often unclear, distorted, smudged, or contains fewer ridges, found overlapping with other prints or appeared on complex backgrounds. As said earlier that a trained and experienced expert is needed for latent print examination because latent print with poor quality, few ridges can give wrong result.
When a fingerprint was found and lifted from a crime scene, it is then send to the concerned department (Finger Print Bureau) to compare with fingerprints stored in a database and against one or more exemplars collected from suspect/persons of interest in the case. The latent print is then searched (from a large database) in an Automated Fingerprint Identification System (AFIS), which is designed to work on an algorithm and selected a list of most similar to the latent comparison. Final decisions were made by a latent print expert. If the expert finds out the same pattern and identified a sufficient number of minutiae in the two prints, then the final “identical” decision is recorded into the computer system, which is again “verified” by a second expert who may or may not be blind to the initial expert decision.
7) The identification process of fingerprint matching is carried out accurately and reliably?
Automated Fingerprint Identification System is used for fingerprint examination. It gives outcomes not just for one single person but for quite a few who have identical fingerprint characteristics. After providing possible candidates list by computer, it’s still the expert call to carefully examines each edge, ridge and valley for a right match—an often hard and painstaking process.
The process for latent print examination is known – ACE-V, (as analysis, comparison, evaluation, and verification).
Analysis – In this step the fingerprint and its suitable area for comparison is examined with clarity of print and other details.
Comparison – The Search print (mostly finger print and in some system palm print) compared with the listed/sample print.
Evaluation – In this step the similar or dissimilar points are evaluated in both prints.
Verification – Opinion is made by one expert and cross checked by another expert.
The process is accurate and reliable.
8) Limitations of fingerprint science
There’s no assurance that the stored data will actually contain the print an investigator is looking for.
Latent print is affected by weather conditions. When the weather is too hot the print is drown by perspiration, when too cold, a print mark not recorded on surrounding objects, due to less moisture. Rain and wind also affect the print condition.
During development of print by powder method the powder can bunch and obscure ridges.
We cannot determine when a latent print was first left on a surface. Under the accurate conditions, prints can survive for an indefinite period.
9) Automated Fingerprint Identification System influenced the experts
The system provides the ordered list of similar matches (also give scoring rate). Experts are more interested in one of the prints that are near the top of the list and not seriously lookout the print lying down the list.
This is only an assumption as the expert check and identifies all the prints in the list provided by the identification system.
10) How many points of comparison are needed in two identical prints to be used in a court of law?
Fingerprint experts used a “point-counting” method that involves counting the number of similar ridge characteristics on the prints, but there is no uniform approach about how many points of similarity are needed. Different countries fixed different minimum point system/similar ridge characteristics. In India there is an 8 point system. When an expert find 8 minimum minutiae (ridge ending, ridge bifurcation etc.) at the relative position in both comparing prints then he reach the conclusion “it’s an identical match”. India accepted the minimum 8 point minutia formula in All India Forensic science Conference held at Srinagar in1973.
So the bottom line is fingerprint science is reliable or accurate, Fingerprint identification is the most important and essential criminal investigation tool, and should continue to be used in criminal investigation. Fingerprint science is a leader of innovation in biometrics for the last two decades.
About The Author
Mr. Deepak Pawar has been working as Finger Print Expert / Police Officer in Fingerprint Bureau, Delhi Police at New Delhi since 2001. He is awarded with Police medal (Utkrist seva padak) by MHA & Delhi Police.